JPH0339618B2 - - Google Patents

Description

[Detailed Description of the Invention] <<Industrial Application Field>> The present invention is a device for use in vehicles that suppresses fluctuations in measured values due to fluctuations of fuel in a tank as much as possible, thereby enabling highly accurate measurement. The present invention relates to a remaining fuel amount measuring device.

≪Prior art and its problems≫ Conventional fuel remaining amount measuring devices for vehicles move up and down according to the liquid level, as seen in, for example, Japanese Patent Laid-Open No. 55-160817 and Japanese Patent Laid-Open No. 56-155813. A float and a resistive potentiometer that is driven in conjunction with the vertical movement of this float are installed in the fuel tank, and the output voltage of this potentiometer is amplified via a DC amplifier, and the output is applied to the remaining fuel. It is known to measure the amount of fuel, and its use was generally to swing a pointer-type analog meter that constitutes a fuel level gauge.

On the other hand, these days, the output of this type of fuel remaining amount measuring device is used to measure the remaining fuel amount with high accuracy (for example, 10
There is a movement toward digital display in units of 0.1 liter or 0.1 liter), and it has become possible to obtain various information using data on remaining fuel level.

As a result of the widening of the range of applications of the remaining fuel amount measuring device, the following problems have arisen when the fuel oscillates within the fuel tank.

In other words, as is well known, when a vehicle turns a curve while driving, starts, stops, accelerates or decelerates, starts going up a slope, finishes going up a slope, starts going down, finishes going down, etc. , a large load is applied to the fuel tank, the fuel in the tank fluctuates greatly, and the apparent remaining amount of fuel fluctuates accordingly.

In this way, if the apparent remaining fuel value changes, the measured fuel remaining amount will also change significantly, but this is not a big problem when using a pointer-type analog meter. . In other words, in the case of a pointer-type analog meter, very high display accuracy is not required, and the meter itself has a slight delay factor due to its structure, so even if the display input changes, the pointer itself will not change much. There is no
Furthermore, even if the pointer fluctuated greatly, the display did not give the driver a particularly uncomfortable feeling from an ergonomic point of view.

On the other hand, in the above-mentioned high-precision digital display, if the display input fluctuates in this way, the displayed values will change and flicker one after another at minute intervals, giving the driver a significant sense of discomfort. In the end, there is a possibility that the reliability of the display will be lost.

Therefore, the present applicant previously proposed in Japanese Patent Application No. 55-83897, etc., a new fuel remaining amount measuring device that can reduce fluctuations in measured values as much as possible even when the fuel in the tank fluctuates. is suggesting.

This fuel remaining amount measuring device is as shown in Fig. 10.
A CR oscillator 2 uses a pair of electrodes 1 placed opposite each other in the fuel in the tank and a CR oscillator 2 whose frequency is variable using the capacitance formed between these pairs of electrodes, to convert changes in the remaining fuel amount into a pulse train. The frequency of the pulse train output from the CR oscillator 2 is approximated or multiplied to a predetermined number of digits by the frequency divider 3, and then the pulse train output from the frequency divider 3 is detected as a periodic change. (Hereinafter, this will be referred to as the averaging time) The counter 4 or 5 counts, and based on the counting result, the calculation unit 6 calculates the remaining fuel level, and displays this on the digital display 7, for example. This is what I did.

The switch position determiner 8 determines whether the ignition switch 9 is on or off, and the output of the switch position determiner 8 controls the switching of the changeover switch 10. For example, when the ignition switch 9 is turned off due to refueling at a gas station, the output of the frequency divider 3 is sent to the counter 5, which has a short averaging time, and the display response is good. On the other hand, if the ignition switch 9 is turned on because the vehicle is running, the output of the frequency divider 3 is sent to the counter 4, which has a long averaging time, and the fluctuation of the fuel liquid in the tank is This will prevent fluctuations in display data due to movement.

However, in the case of the remaining fuel amount measuring device having such a configuration, a simple time averaging method using the counter 4 is adopted as a means to suppress fluctuations in the measured value due to fluctuations of the fuel in the tank, so the measured value In order to sufficiently suppress fluctuations in the measured values, it is necessary to lengthen the averaging time in the counter 4, and as a result, the more you try to suppress the fluctuations in the measured values, the longer the update cycle of the measured values becomes, and the longer the measurement This will impair responsiveness.

On the other hand, if the averaging time in the counter 4 is set to be relatively short in order to keep the measurement response within the allowable range, it will not necessarily be possible to sufficiently suppress fluctuations in the displayed value due to fuel fluctuations, and the averaging time will actually be shorter. Even if the time is set to about 1 to 2 minutes, the remaining amount indicated on the display 7 will be ±1 to 2 minutes.
There was a problem that it fluctuated by about 2 degrees.

≪Object of the Invention≫ This invention was made in view of the above-mentioned technical background, and its purpose is to sufficiently suppress fluctuations in measured values due to fluctuations of fuel in the tank, and to improve measurement response. An object of the present invention is to provide a good fuel remaining amount measuring device for a vehicle.

<<Configuration of the Invention>> The configuration of the present invention will be described with reference to the claim correspondence diagram in FIG.

The remaining fuel amount detection means a detects the amount of fuel remaining in the tank.

The sampling means b samples the detected remaining fuel amount value in time series.

The time series storage means c compares the detected remaining amount value obtained for each sampling time with the latest remaining amount moving average value, and if the deviation between the two is within an allowable range, the sampled detected amount is The remaining amount value is stored as it is as the latest detected remaining amount value, and if it is outside the tolerance range, a certain small value is added or subtracted from the latest moving average value depending on the polarity of the deviation. Store as the latest detected remaining amount value.

The moving averaging means d obtains a moving average value of the detected remaining amount values for a predetermined number of times in the past, which are stored in the time series storage means c.

The obtained moving average value is then output as a measured value.

<<Description of Examples>> Examples of the present invention will be described in detail below with reference to FIGS. 2 to 9.

FIG. 2 is a block diagram schematically showing an entire embodiment of the remaining fuel amount measuring device according to the present invention, FIGS. 3 to 7 are diagrams showing an example of a specific structure of an electrode pair, and FIG. Figure 8 is a block diagram showing the hardware configuration of the signal processing circuit shown in Figure 2 when it is configured with a microcomputer, and Figure 9 shows the configuration of a system program executed by the microcomputer shown in Figure 8. It is a flowchart.

In FIG. 2, the electrode pair 11 is immersed in the fuel in the fuel tank and placed facing each other, and an example of its specific structure will be described with reference to FIGS. 3 to 7.

As shown in FIGS. 3 and 4, the fuel tank 1
The outer shell of No. 2 is divided into upper and lower halves, an upper shell 12a and a lower shell 12b, and inside thereof is a buttful plate 1 fixed directly to the inner upper surface and side surface of the upper shell 12a by spot welding or the like.
3 and 14, and is configured to prevent the generation of noise due to rapid movement of the fuel 15.

Electrode plates 16, 17, 18 are arranged facing each other on the surfaces of the baffle plates 13, 14 with a certain gap between them.
As shown in FIG. 5, these electrode plates 16, 17, and 18 are attached to the buffle plate 1 with rivets 20 via insulating spacers 19 so as not to be electrically conductive with the buffle plate.
3 and 14, respectively.

A predetermined gap is provided between the lower end edges of the baffle plates 13, 14 and the bottom wall of the fuel tank, that is, the lower shell 12b, so that they do not come into contact even if the lower shell 12b undergoes some elastic deformation.

At the upper ends of the buttful plates 13 and 14, there are flanges 2 that serve as joints with the upper shell 12a.
1 is provided in an appropriate number, and among the flanges 21 of these buttful plates 13 and 14, at least two flanges 21 that are relatively apart from each other,
A notch 22 is provided for positioning during assembly.

On the other hand, the upper shell 12a is provided with a protrusion 23 which is a marker for positioning the buff-full plates 13, 14 and corresponds to the notch 22 of the flange 21 on the buff-full plates 13, 14 side.

As shown in FIGS. 6 and 7, the electrode plates 16, 1
7 and 18 are predetermined electrode plates provided on a circuit board in a box 25 whose lower ends are connected to each other by a conductive harness plate 24 and further fixed to the upper outer side of the upper shell 12a via a harness (not shown). Connected to the connection terminal.

Next, returning to FIG. 2, the CR oscillator 26 includes the buffer plates 13, 14 and the electrode plates 16, 17, 18.
The oscillation frequency is changed depending on the capacitance formed between these electrode pairs. It can be configured with a known CR oscillation circuit mainly based on.

Next, returning to FIG. 2, the frequency divider 27
The frequency of the pulse train output from the oscillator 26 corresponding to the remaining amount of fuel is divided, and by the frequency dividing operation by the frequency divider 27, the oscillation pulse train is subjected to a predetermined frequency approximation or rounding process.

Specifically, the functions of the signal processing circuit 28 are performed by executing a system program as shown in FIG. 9 by a microcomputer having a hardware configuration as shown in FIG.

That is, in FIG. 8, the microcomputer 31 has an input interface 311 for receiving the output of the frequency divider 27 and the output of the ignition switch 29, and sends the display output obtained by calculation to the display 30. an output interface 312 and an input interface 31 for
A presettable down counter (hereinafter referred to as the first counter) that is controlled to count down every time a pulse is supplied from the frequency divider 27 to 1.
313, a clock generator 314 that generates a clock pulse as a time reference, and a presettable up counter (hereinafter referred to as a second counter) 315 that counts up the clock pulses output from the clock generator 314.
, a memory section 316 composed of a ROM for storing system programs, a RAM used as a working area, etc., the input interface 311 and the output interface 3 described above.
12, first counter 313, clock generator 314, second counter 315 and memory section 3
16 and a CPU 317 that centrally controls the 16.

Next, while referring to the flowchart in Figure 9,
The operation of this embodiment device will be systematically explained.

First, when the program starts, step 1
is executed, and the first counter 313 is preset with a numerical value Z corresponding to the number of pulses required for average period measurement. Here, the value of the numerical value Z is determined by taking into account the fluctuation range in which the output frequency of the frequency divider 27 changes while the fuel tank changes from an empty state to a full state. While the tank changes from empty to full, frequency divider 27
The output is configured to vary within a range of approximately 1.0Hz to 0.5Hz.

Therefore, if Z=10 and the average period of 10 pulses is to be measured, it will take 10 to 5 seconds.

Next, when step 2 is executed, the second counter 315 is set to an initial value of zero. From then on,
The second counter 315 is the clock generator 31
The clock pulses outputted from the second counter 4 are counted up, and the count value of this second counter becomes data on the time required for Z pulses, as will be described later.

Next, when step 3 is executed, CPU3
17 repeatedly checks the count value of the first counter 313 and remains in a standby state until the count value becomes zero. Then, upon completion of counting Z frequency-divided outputs, the count value of the counter 313 becomes 0, and at the same time, the execution result of step 3 becomes YES, and step 4 is then executed.

When step 4 is executed, the CPU 317 has the following information:
The count value of the second counter 315 at that time is taken in and stored in the average period register T provided in the working area. Here, since the second counter 315 is set to zero at the time when the numerical value Z is set in the first counter 313, the count of the second counter 315 at the time when the count value of the first counter 313 becomes 0. The numerical value indicates the total period of exactly Z frequency-divided pulses, that is, this value corresponds to the average period of Z frequency-divided pulses.

Next, when step 5 is executed, the output of the ignition switch is input to the CPU 317 via the input interface 311, and depending on the content, it is determined whether the ignition switch is on or off. A judgment is made.

Here, when the vehicle is running, the ignition switch is turned on, so the execution result of step 5 is NO, and step 6 is subsequently executed.

When step 6 is executed, it is determined whether the value of the average cycle data obtained in step 4 is a normal value or an abnormal value. This determination is made by determining whether there is a relationship |T-T'|≧α between the contents of the average period register T and the contents of the moving average value register T', which will be described later.

Here, the value of the numerical value α is set to correspond to 0.5 of the fluctuation range of the remaining amount value when the fuel in the tank fluctuates.

Therefore, if the fuel in the tank fluctuates and its apparent remaining amount fluctuates by more than 0.5, and the contents of the average period register T become an abnormal value accordingly, the execution result of step 6 becomes YES.

Here, in the case of this embodiment device, when the vehicle moves from a slope to a flat road, data for moving average processing is prevented from being retained without being updated for a long period of time. Special measures have been taken to achieve this.

That is, assume that the vehicle is currently stopped on a slope and is moving from the slope to a flatter road. In this case, for example, on a slope, it is assumed that the detection unit detects a value about +3 more than the actual remaining amount. On the other hand, when the vehicle goes out onto a flat road, it is assumed that the fuel gauge measures a value that fluctuates by ±2 from the actual remaining fuel amount while driving.

Under such circumstances, there is a possibility that the value measured by the fuel gauge on a flat road will be about 1 lower than the initial value on a slope.

Therefore, if the abnormality judgment width α is set to ±0.5, the signal from the detection unit on a flat road will always exceed this abnormal value removal width, and the data subjected to moving average processing will be retained as is. There is a risk that it will not be updated for a long time.
In other words, there is a problem in that the fuel remaining amount indication value does not change even though fuel is actually being consumed.

The above-mentioned disadvantages are solved in this embodiment as follows. In other words, the execution result of step 6 is
If YES, then step 12 is executed, and it is determined whether the difference between the obtained average cycle data value and the previous moving average value is positive or negative.

If it is determined to be positive, step 13 is executed, whereas if it is determined to be negative, step 14 is executed.

When step 13 is executed, a value obtained by adding a numerical value δ to the previous moving average value is stored in the first stage register _T0 constituting a shift register to be described later, and when the other step 14 is executed, ,
The value obtained by subtracting δ from the previous moving average value is stored.

Here, the value of δ is determined in accordance with periodic data for fluctuations in the remaining fuel amount of about 0.1.

As a result, if the average cycle data obtained in step 6 is determined to be abnormal as described above,
Furthermore, if it is determined that the remaining fuel value is increasing, the data that has increased by 0.1 from the previous moving average value is taken in for the moving average processing, and if the remaining fuel value is decreasing, the data is taken in for the moving average processing. If it is determined, the value similarly decreased by 0.1 will be taken in for the moving average processing.

Therefore, as mentioned above, even when leaving a slope and moving onto flat land, the value of the moving average value gradually increases or decreases in the subsequent process, and as a result, when approaching flat land, the moving average value gradually increases or decreases. The difference between the average cycle data value and the moving average value gradually decreases to ±
Once it is within 0.5, as long as there is no shaking in the tank, the average cycle data obtained will be correctly imported as data for moving average processing, which may impede display responsiveness. This means that it will disappear.

On the other hand, when the fluctuation of the fuel in the tank is relatively gentle or it is stationary,
The execution result of step 6 is NO, and then step 7 is executed, and the contents of the average period register T are stored as they are in the first stage register _T0 .

Next, step 8 is executed to perform moving average processing. For this moving average processing, m
registers T ₀ , T ₁ , T ₂ ...Tm− ₁ are used,
These registers function as a shift register as a whole through software processing, and the register
T ₀ , T ₁ , T ₂ ... are the first shift registers, respectively.
It corresponds to stage, 2nd stage, 3rd stage...

Then, based on the contents of each register T ₀ , T ₁ ...Tm- ₁ , the moving average value of m pieces of average period data is determined by the following formula, and this moving average value is stored in the moving average value register T'. be remembered.

T' = (T ₀ + T ₁ + T ₂ +...Tm- ₁ )/m Next, when step 9 is executed, the remaining fuel amount value is determined by the following formula based on the contents of the moving average value register T', It is stored in the remaining amount register Q.

Q=[(T'-β)/β]×K Here, the value of the numerical value β is determined corresponding to the average cycle data when the fuel tank is empty, and the numerical value K corresponds to the capacity of the tank. Determined by

Then, when step 10 is executed, the contents of the remaining amount register Q are provided as a display output to the digital display 30, thereby causing the digital display 3
At 0, the remaining fuel amount value is displayed in units of 1, for example.

On the other hand, if the ignition switch is turned off and refueling is in progress, the execution result of step 5 is YES, and step 11 is subsequently executed.

When step 11 is executed, the contents of the average period register T are immediately stored in the moving average value register.
T', and steps 9 and 10 are then executed as described above.

As a result, if the contents of the average cycle register T rapidly increase over time due to refueling, the average cycle data obtained one after another under such conditions will not be regarded as an abnormal value.
It is immediately used as data for calculating the remaining amount,
During refueling, the display response of the display becomes good.

Thereafter, while the vehicle is running, the average cycle register T
The sequentially detected average cycle data is stored in
Only if the value of the obtained average period data is normal, the register group that makes up the shift register
The average cycle data is taken into the first stage register T ₀ of T ₀ to Tm− ₁ , and at the same time, the contents of each register are sequentially sent one by one to the next stage, and in this state, the register T ₀ of each stage ~Tm−
Based on the contents of _{No. 1} , a moving average value of m pieces of data is determined, and a remaining fuel amount value is determined based on this moving average value and is sequentially digitally displayed on the display.

In addition, when the vehicle is being refueled, the average cycle data obtained above is sequentially transferred to the moving average value register and immediately used as data for calculating the remaining fuel amount, so the display during refueling It does not impair responsiveness.

Thus, according to the device of this embodiment, the average cycle data obtained sequentially through steps 1 to 4 is not immediately used for calculating the remaining fuel amount, but is further subjected to moving averaging processing and then used for calculating the remaining fuel amount. Therefore, even if the average cycle data is disturbed due to fluctuations in the fuel in the tank, the fluctuations in the remaining fuel amount based on this will be relatively small, and the obtained fuel remaining value will be Even when quantity values are displayed on a digital display, for example, display flickering can be reduced as much as possible.

In addition, the sequentially obtained average period data is compared with the previously obtained moving average value data, and if the average period data corresponds to an abnormal value, the value obtained by adding or subtracting a certain small value to the previous moving average value is calculated. By adopting this method, even when reaching a flat road after going up a long slope, the measured value can be prevented from becoming fixed and the reliability of the display can be improved.

In addition, it detects whether the vehicle is refueling through the on/off state of the ignition switch, and in this case, the remaining fuel is calculated based on the average cycle data immediately obtained without performing moving average processing. Since the quantity value is determined by calculation, the display response during refueling is not affected.

Furthermore, the display update period during driving and refueling is mainly determined by the numerical value Z set in the first counter 313, and even if the value of this numerical value Z is set to a small value and the sampling interval of the average period data is shortened. Since moving averaging processing is then performed, there is little effect on fluctuations in the final remaining fuel amount value, and therefore the display data update cycle can be made shorter than in conventional devices.

In the above embodiment, the output of the ignition switch was input into the CPU as a means for determining whether the vehicle was being refueled. Of course, for example, the output of a vehicle speed sensor may be taken in and based on this it may be determined whether the vehicle is stopped, that is, refueling.

Furthermore, in the above embodiment, the remaining amount detection data generating means is composed of an electrode pair and a CR oscillator, but the configuration of the remaining amount detection data generating means is not limited to this. It is also possible to construct it from a conventionally used float type potentiometer and an A/D converter for A/D converting the output thereof.

<<Effects of the Invention>> As is clear from the description of the embodiments above, the remaining fuel amount measuring device according to the present invention is more effective in reducing fluctuations in the fuel in the tank than in devices using conventional simple time averaging processing. This makes it possible to suppress fluctuations in the measured value of the remaining fuel level when the fuel level is measured, as well as improve measurement responsiveness. It is possible to reduce flickering, and furthermore, when the remaining fuel amount measurement value is used as input data for other controls, it is possible to further improve the control accuracy.

Furthermore, in the present invention, even if the value of the obtained detection data is significantly different from the previous moving average value, the latest detection data is determined by adding or subtracting a predetermined small value according to the deviation between the two. , has the excellent effect of suppressing fluctuations in measured values due to noise without impairing responsiveness.

[Brief explanation of drawings]

FIG. 1 is a claim correspondence diagram showing the structure of the present invention;
Fig. 2 is a block diagram showing the schematic configuration of the remaining fuel amount measuring device according to the present invention, Fig. 3 is a partially cutaway plan view of the fuel tank showing the attached state of the electrode pair, and Fig. 4
The figure is a longitudinal sectional view of the same, and Figure 5 is the same as in Figure 3.
6 is a plan view of the electrode pair, FIG. 7 is an elevation view thereof, FIG. 8 is a block diagram showing the hardware configuration of the microcomputer of the embodiment device according to the present invention, and FIG. 9 is a plan view of the electrode pair. FIG. 10 is a flowchart showing the system program of the microcomputer, and is a block diagram showing the configuration of the remaining fuel amount measuring device previously proposed by the applicant. a...Fuel remaining amount detection means, b...Sampling means, c...Time series storage means, d...Moving average value means.

Claims (1)

[Scope of Claims] 1. Remaining fuel amount detection means for detecting the remaining fuel amount value in the tank; Sampling means for sampling the detected remaining fuel amount value in time series; Compare the detected remaining amount value with the latest remaining amount moving average value, and if the deviation between the two is within the allowable range, the sampled detected remaining amount value is stored as is as the latest detected remaining amount value. In addition, when the value falls outside the allowable range, a time-series storage means stores a value obtained by adding or subtracting a certain small value from the latest moving average value depending on the polarity of the deviation as the latest detected remaining amount value. ; a moving average means for calculating a moving average value of the detected remaining amount values for a predetermined number of times in the past stored in the time series storage means; for a vehicle, characterized in that the moving average value is output as a measured value. Fuel remaining amount measuring device.